1. Field of the Invention
The present invention relates to a coil component used in a power supply circuit and the like for a mobile device such as a mobile phone.
2. Description of the Related Art
As a conventional coil, an inductor laminated ferrite sintered bodies which have respectively a built-in conductor, has been widely used as disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2005-268369. In the inductor, a core body is very brittle and is fragile against bending and shock impact. For this reason, when the inductors are used in power supply circuits and the like for a mobile device, a problem arises in that it is liable to be broken by deflection, deformation due to elapse, or dropping impact of a substrate.
To solve the problem, there is proposed a flexible inductor configured such that a compound magnetic material (compound magnetic sheet) obtained by mixing a magnetic powder with a resin is layered on a film type coil, as shown in JP-A-2006-303405 and the corresponding US Publication No. US2006/0214759A1. The flexible inductor has a mechanical advantage in that it is less brittle, can be mounted on a flexible printed board, and is resistant against deflected deformation and drop shock.
However, since recent mobile device is to more reduce its size and to more increase an output, the flexible inductor disclosed in US2006/0214759A1 is also required to more improve an inductance value.